This invention relates generally to automobile seats and more particularly to a method for forming a contoured portion of a vehicle seat or vehicle seat back having contoured styling features.
Various methods of bonding a breathable vehicle seat cover material to an underlying foam bun have been used to form contours or style lines in the surface of vehicle seats. One such method is disclosed in U.S. Pat. No. 4,692,199, issued to Kozlowski et al on Sept. 8, 1987.
The Kozlowski method comprises laying a cloth fabric on top of a contoured porous mold surface and overlaying the cloth fabric with an impermeable adhesive film. The film is physically secured and a vacuum is then drawn through the mold so as to cause the impervious film to draw the cloth fabric down into conformity with the contour of the mold surface. A foam pad is then compressed against the mold and the vacuum discontinued. Steam is then applied to heat and diffuse the adhesive film into the adjacent fabric layer and the foam pad to secure the two together. The adhesive film is not a part of the cloth fabric and therefore can gather during vacuum drawing such that wrinkles or creases in the adhesive film are created. These wrinkles can cause uneven adhesive thicknesses over the contoured surface. The uneven thickness can cause adhesive saturation of the fabric which can destroy the outer surface appearance of the fabric. Close visual scrutiny of the operation during the application of the adhesive film to the cloth fabric and to the foam bun or cushion pad is therefore required.
The method according to the present invention eliminates uneven adhesive thickness and minimizes the potential for adhesive breakthrough. The method according to the present invention comprises placing a sheet of air impermeable material such as a polyolefin film against a sheet of permeable cloth fabric to form an impermeable fabric composite. This impermeable fabric composite is then positioned on a forming tool having an upper surface having a shape complementary to the desired predetermined vehicle seat surface shape and having vacuum ports therein.
The fabric trim material composite is positioned over the forming tool with the cloth fabric against the upper shaped surface. A vacuum is drawn between the impermeable material composite and the upper surface of the forming tool. Atmospheric pressure then presses against the polyolefin sheet pressing the material into conformity with the contours of the upper surface of the tool. A foam bun with an adhesive on one face is then positioned against the material composite on the tool and heat is applied to the forming tool. The heat destroys the impermeable barrier created by evaporates the polyolefin film and enables the adhesive to contact the cloth fabric so as to adhere the bun to the fabric. This destruction of the impermeability of the film may be accomplished by evaporation, melting, vaporizing, deteriorating or other method.
The presence of the polyolefin film prevents excessive permeation of the cloth fabric with adhesive so as to preclude damage to the outer surface of the fabric. Excessive permeation of the cloth fabric with adhesive is prevented by removing an inherent limitation involved with the use of an impermeable adhesive film. If the adhesive film gathers and wrinkles or creases during vacuum drawing, the subsequent application of heat will result in the formation of a large amount of adhesive in place of the wrinkle or crease. This large amount of localized adhesive can cause saturation of the fabric and destroy the outer surface appearance of the fabric. The present invention avoids such a result by directly controlling and evenly applying the adhesive to the foam bun. Thus, the formation of a wrinkle or crease in the impermeable polyolefin film during the vacuum forming step of the present invention will not cause adhesive to saturate the cloth trim fabric and destroy the appearance of the fabric. The result is a readily repeatable process in which various style lines can be produced in vehicle seats having cloth covers which are permeable to enable the seat to breathe. Fabrics for such covers are also advantageous from a cost standpoint.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims, when taken in connection with the accompanying drawing.